Recs.
Updated
SpecsUpdate
Pros
Pro Great for making simple or complex Text-Based RPGs
Using the different macros correctly can allow you to make simple linear RPGs or the more complicated decision-based RPGs. Not true to the CON listed below, you can do so much more than just interactive fiction. If you don't know what your doing, just tell the nice people on the Discord server what you're trying to do, and they will gladly help. Also, once you can figure your way around the more complicated code, you can start adding visuals to your game as well.
Pro Large website dedicated to teaching the commands to learners
Twine has a large website containing every macro for the Harlowe story format, I don't use the others so I don't know about them, as well as a description of how they work coupled with an example. The website makes coding with twine even easier.
Cons
Con Limited to interactive fiction
Twine is specialized to decision-based interactive fiction. Under the hood, a Twine game is just a flowchart for page transitions; the only way to add more complex behavior is to code it from scratch in JavaScript, unless you know your way around the {if, elseif, then} commands.